All of that snow in your picture is what has me stumped. So let me tell you what we do and see if it can be done up there. First of all is there any way you can remove 1 or 2 trees or more? If not fine but it makes it a lot easier. If you can just lay down a non beneficial tree or trees it will be great.
As for shade tollerant you are never going to get the yields of full sun. Secret spot is just rye grass and cereals with a little brassica in it. In general rape, collards, turnips, beets and kale with a lyme filler. For me to buy locally the setup is about $20 to get the same blend as whitetail institute, less the lyme, which is not enough(lyme) for woodland. So I just buy it in the plot bag.
The idea is to plant a little earlier than you could normally get away with, late summer. The shade keeps the plants from burning up. When the leaves fall there is a short growing season until hard frosts come on. Some other plants you can do this with are Partridge Pea, Cowpea, Plantain(broadleaf perrenial), Certain clovers Ladino, Crimson and Arrowleaf. Be advised the clovers need a lot more lyme and moisture than anything else listed. Small Burnett is a good little perrenial forb that is cold hardy that has migrated to the shade on my place.
If you can lay down any trees, line the north side of the plot's tree line with honeysuckle. The south with the shade seed and the center with a good high protein perrenial such as new zealand type clover. The annuals will often reseed themselves. All this is assuming that the deer will paw the snow to get to the plants. And that the snow insulates them instead of killing them. I have no idea thankfully. If farmers grow winter wheat in your area it most likely can be done.
Blessings